The demand for natural gas in the United States and worldwide energy markets is continually rising because it is viewed as a viable and clean alternative to traditional oil and coal. Natural gas is of particular importance because it is produced domestically and currently accounts for more than one-fifth of all the primary energy used in the United States. Furthermore, it is essential to the residential sector where it supplies nearly half of all the energy consumed in United States. The United States currently has proven natural gas reserves totaling 354 trillion cubic feet.
However, significant quantities of natural gas reserves in the United States cannot be produced economically because its quality is too low to be transported via existing pipeline infrastructure. Such low-quality natural gas contains significant concentration of gases other than methane. These non-hydrocarbons are predominantly nitrogen, water, carbon dioxide, and hydrogen sulfide, but may also include other gaseous components. These impurities significantly decrease the BTU value of the gas per unit volume and dramatically increase the transportation cost.
Most interstate pipeline systems in the United States have specifications that mandate the nitrogen content in the natural gas cannot exceed four to five percent. However, roughly fourteen percent of known gas reserves in the United States contain nitrogen in excess of the five percent threshold. These reserves either have a discounted market potential or are completely unmarketable due to the difficultly and cost inefficiency of removing the excess nitrogen. Consequently, there is a need to develop an efficient and cost effective method to improve the low-quality natural gas reserves in the United States.
Numerous attempts have been made to address the treatment of natural gas, and in particular, the removal of nitrogen, but these attempts can generally be divided into four major classification:                a. Methods for the low temperature and high pressure fractional distillation of low-quality natural gas.        b. Methods that utilize selectively nonporous membranes to separate the methane from other gas contaminants.        c. Methods for the adsorption of methane using activated charcoal as the methane adsorbent.        d. Methods that induce a chemical reaction between reactive elements and the nitrogen in the natural gas.        
Although the aforementioned methods have achieved some success, in general the methods are too complex and prohibitively expensive at modest scale. Fractional distillation and adsorption methods are particularly inefficient because they remove the major component, methane, from the minor component, nitrogen, which increases cost and inefficiency. Similarly, methods using selectively nonporous membranes are economically inefficient and complex because they require low temperatures, and most membrane materials have low selectivity to methane and nitrogen. Finally, many of the existing methods require large centralized facilities to remove the nitrogen from the natural gas and exhibit poor scale down economics.
Within the chemical treatment of natural gas classification, U.S. Pat. No. 2,660,514 discloses one non-limiting example of a process for the removal of nitrogen. The disclosure includes a process for producing lithium nitride by the reaction of lithium amalgam with natural gas. The lithium nitride is subsequently reacted with water to produce ammonia and lithium hydroxide. The lithium hydroxide is then electrolyzed to regenerate the lithium amalgam.
Although the lithium amalgam method has been used to separate nitrogen from natural gas, it suffers from the following drawbacks: (1) lithium amalgam is not as efficient as lithium metal in removing nitrogen, (2) lithium amalgam contains mercury, and mercury is not preferred due to its hazardous nature, and (3) lithium hydroxide is a stable compound and it's electrolysis is an energy intensive process requiring high voltage (˜4V). Moreover, the described process is applicable only for regeneration of lithium amalgam and not applicable for lithium metal.
In view of the multiple deficiencies of existing methods, there remains an unsatisfied need for a scalable, efficient, economical, and safe means of removing nitrogen from natural gas.